This invention relates to alternator tuning devices, particularly to alternator isolating decouplers (AID) with torsion springs for isolation. The function and utility of alternator tuning devices is commonly known. Commercially available AID devices typically comprise an isolating spring, one way clutch, bearing(s), a pulley and certain other components which may include spring carrier(s). The need for each of these components typically requires the overall size diameter of the device to exceed what the industry desires. With ever smaller automotive engine sizes and ever increasing fuel efficiency requirements, there is a need for AID devices that have a reduced pulley diameter while meeting the required functionality. There is also a need for reduced complexity, simplified manufacture and commensurate reduction in overall cost.
Representative of the art is U.S. Pat. No. 8,888,619 which discloses a method for producing an over-running decoupler that is configured to transmit rotary power between a rotary member and a hub. The over-running decoupler includes a one-way clutch having a clutch spring, a carrier that is coupled to the clutch spring and at least one spring that resiliently couples the carrier to the hub. The method includes: establishing a desired fatigue life of the at least one spring; establishing a design deflection of the at least one spring during resonance, wherein deflection of the at least one spring at the design deflection during resonance does not reduce a fatigue life of the at least one spring below the desired fatigue life; and preventing resonance in the over-running decoupler by controlling a maximum deflection of the at least one spring such that the maximum deflection is less than or equal to the design deflection.
What is needed is an isolating decoupler comprising a torsion spring directly connected to a hub by welding, and a wrap spring directly connected to the torsion spring by welding. The present invention meets this need.